Machine-switching telephone system



March 18, 1924. V y 1,487,113

' A. E. LUNDELL MACHINE SWITCHING TELEPHNE SYSTEM w L Qc' I Y 1 4 /nvenlar- 1 Alben E. Lande/l.

by R .YI wlw/1 tt Y ALBEN E. LUNDELL, or NEW YOEK, N. Y., nssieNoE 'ro WESTERN ELEOTRIO'GOM- PANN, INCORPORATED, n OoEroEA'rrON or NEW YORK.

l IVIACHINE-SWITCHING TELEPHONE SYSTEM.

Application led December 18, 1920. Serial No. 431,558.

.To all whom it may concern:

Be it known that I, ALBEN E. LUNDELL, a citizen ofthenUnited States, residing at New York, inthe county of Bronx, State of New York, have invented certain new and useful Improvements'V in yMachine- Switching Telephone Systems, oit' which the ollowingis a full, clear, concise, and exact description. f

ThisA invention relates to telephone eX- change systems, an-d more particularly to machine switching telephone systems'y in which provision is vmadefor supplying subscribers Withmeasured service.

rlhe three main classes of service usually supplied to subscribers, are either measured service, in which case, a message register is used to count the number of calls, coin box service, in which the subscriber pays .for each call as it is made, and'tlat rate service, in which the subscriber'merely pays a iiXed amount of money for the use of his telephone over a fixed period of time.' Methods .for operating message registers and coin collect devices are well-known in the art. Since,

howevendiferent methods are employed to collect a coin from those required to operate a message register, ithas been the previous practice to segregate the subscribers in accordance with the class of service to which they are entitled so that upon completion of a successful call, their charging devices may be operated by the proper character of current. This arrangement is satisfactory so long' as the subscribers may be divided into equal groups, but it frequently happens that there will remain a fraction of a groupof subscribers entitled to each kind of service. To give each of these small groups of subscribers access to a particular type of switch arranged for meeting the requirements of their particular type of toll device, results in an inefficient use of the apparatus. f

It is the object of this invention to pro-V vide a switching arrangement .such that a number of lines, which differ with respect to the class of service to which they are entitled, may all have access to the same type of Vfirst selector, and in case Vof successful calls, the charge will be properly made.

A feature of the invention is the setting up of a discriminating` condition in the first selector, switch circuit, 'which j will, at the proper time,Y determine the typelof charging apparatus to be put into use.

A further feature of the invention resides in fthe use Vof various resistances. bridged across theline conductors tocontrol a relay combination at the` selector purpose above setiforth. Y

It is thought thatthe -invention will be best understood romthe following detailed description, reference being. had to the accompanying drawings.

In the drawings, Eig. 1shows diagram- Switch for thev matically, the-substation circuits of three 'i subscriberslines; the first being a fiat rate line,v the second a coin .box line, and the third, a message register line.: The 4circuits of a line inderland auxiliary apparatus 4are also shown in this figure.` Fig. 2 showsV such portions of a iirst selector switch and the sending and registering devices `as are necessary to' a complete understanding of the invention. v Y v The invention has been shown applied to a full automatic system employing switches ofthe, type set forth in Patent No. 1,123,- 696, 'issued January 5, 1915,;to E. BfCraft and J. N. Reynolds. -ltis-to be understood,

however, that the system shown is for the Vpurpose of illustrationonly, and the invention is, therefore, not to be restricted thereto. A description of the operationof the system, when a flat rate subscriber initiates a'call, will first be given.

l/Vhen the subscriber atV substation l removes his receiver'from `the hook, acircuit is completed from grounded battery, winding of line relay 2, left-hand armature and back Contactv of cut-O relay 3, conductor 4, the substation apparatusA of the calling subscriber, conductor 5, and the' right-hand Varmature and back contact of relay 3 to ground. Relay 2 is energizedk in this circuit and completes a circuit from grounded battery, winding of relay 6, side switch arm 7 and its'iirst contact, conductor 8, and thearmature and front vcontact, of relay 2 to ground. Relay -isV energized in this cirf cuit and completes a circuit from grounded battery, winding of side switch magnet 9, and the armature and front contact of relay 6 Vbe deenergized and supply ground to ground. Magnet 9 is energized in this circuit, and causes the advance of the side switch out of position 1 and into position 2.

With the side switch in position 2, relay 6 'is maintained energized over a circuit eX- tending rom grounded battery, winding of relay 6, side switch arm 10 and its second contact, test brush 11 and its first contact to ground. 1t is to be noted that the first and second contacts served by brush 11 are permaiiently connected to ground. `Witli the side switch in its second position and with relay 6 energized a self-interrupting circuit for line finder stepping magnate 12 is conipleted extending from grounded battery, winding of magnet 12, armature and back contact of magnet 12, side switch arm 13 and its second contact, armature andiront contact of relay 6 to ground. Magnet 12 is energized and interrupts its own circuit, and upon deenergization causes the line iinder brushes 14, 15, 16, 11 and 17 to be moved into engagement with their second contacts. r1`he line iinder switch is a single motion rotary switch which may be of any well-known form. 1n the present embodiment of the invention it has been assumed that this line finder switch is of the type shown 'and described in an application, Serial No. 317,126, tiled August 13, 1919, by O. F. Forsberg and R. M. de Vignier.

When test brush'll engages its second contact, relay 6 is maintained energized over a circuit identical with that previously described. As a result of the continuous energization of relay 6 magnet 12 is again energized and interrupts its own circuit to advance the line finder brushes into engagement with the third set ot contacts. rlChe hunting operation of' the line tinder switch begins at this point and will continue, due to the fact that magnet 12 will continue to interrupt its own circuit and advance theline iinder switch as long as relay 6 remains energized. Relay 6 remains energized as long as test brush 11 is passing over the terminals of non-calling lines. The terminals of non-calling lines, whether busy as calling or called subscribers, or o1 idle lines, will be characterized by the presence oi ground potential on their respective test terminals in the line finder bank.y due to the fact that the line relays oi such lines will potential by way of their righ'ohand armatures and back contacts to such test terminals, as is obvious from inspection of the drawings.

l/Vhen the line finder brush set engages the terminal set of the calling subscribers line, relay 6 will be deenergized, since no ground potential will be Jfound by brush 11, due to the fact that line relay 2 is energized. Relay 6 will therefore become deenergized and prevent further operation oi magnet 12,

mamie thus causing the brush set to remain in engagement with the terminals of the calling subscribers line. The deenerrfization olrelay 6 also opens the original energizing circuit for side switch magnet i) and this relay deenergizes and causes the side switch to be moved into its third. position.

ln position 3 of the side switch, marginal relays 18 and 19 have an opportunity to iFunction in order to register the class of service, with regard to call charging, which shall be provided by the selector circuit.

Since the calling subscribers line is a di rect or lat rate line, that is, provided with neither a message register nor a coin bon, ground potential will be supplied at this time to the tip conductor of the line by way oi the right-hand armature and back contact oi cut-oli' relay 3. vBattery potential is supplied to the ring conductor ot the line by way el the low resistance winding et line relay Relay 19 is energized due to the closure ot a circuit extending from grounded battery, right-hand winding ot' relay 19, side switch arm 20 and its third contact, brush 111, tip conductor 21 to ground, armature and baci; contact oi relay 19 is energized and locks up'tlirough its leithand winding and leftdiand armature and .Lowa

'front contact to conductor 25, which is grounded at the lower lett-hand contact of sequence switch spring 26.

A circuit is completed at the same time for relay 18. This circuit extends from grounded battery, left-hand winding of relay 18, rside switch arm 21 and its third Contact, brush 15, ring conductor 27, through the substation apparatus, aiid to ground at the righthand armature and back contact oit cutoff relay 3. T he winding o1c relay 18 i, however, shunted by 'the low resistance relay 2, to prevent the energization of relay 1t is to be noted that with the side switch in position 3 a circuit is completed from grounded batteij, winding of slow pull up relay 28, side switch arin 23 and its third contact to ground. Relay 28 becomes energized and starts to attract its armature, but since itis slow to pull up relays 18 anl 19 have an opportunity to pull up and loci; to

conductor 25 before relay 28 complet the attraction of its armature, ilJhen the ari ature orn relay 28 is completely attracted i. cir cuit is completed from grounded tat ery.

winding o' side switch magnet 9, sid

the right-hand f winding oiC 13 and its fourth contact, conductor 29, upper left-hand contact of sequence switch spring 26 to ground.

In position 4 of the side switch, cut-off re- 5 lay 3 is energized by a circuit extending from subscribers dial, who may now send impulses to control the setting of such registers.

It is to be understood that the Vinvention is capable of adaptation to the system of any desired capacity. For the sake of simplifying description it has been assumed that the line finder switch is directly connected to a final switch and that there are only onehundred subscribers in the system. The mechanical structure of the switch, whose controlling circuits are shown 1n Fig. 2 is a simplification of the switch shown in Patent No. 1,123,696, issued January 5, 1915 to E. B. Craft and J. N. Reynolds, and is of the well-known power driven panel type selector. In the present case it has been assumed that one brush only is provided and that this brush has access to ten groups of ten lines each. rlhe step-by-step registers, as part of the sender, are of a mechanical structure substantially similar to thatv shown in the application mentioned above in connection with the line finder switch. lt is to be understood that in a practical'systein the sender would be associated with the selector switch by means of a sender selector or a cordfinder and that .a number of these senders would be common to the various selector and finder units. VFor the sake of simplicity it has been assumed that there is asender permanently associated with each connecting link.

With'theside switch in position 4a circuit is completed from grounded battery, winding of stepping relay 32, conductor 33, side switch arm 21 and its fourth contact, brush 15V and its associated contact, conductor 27, through the substation apparatus Y of the calling subscriber including a sending device 34, conductor 24, brush 14 and its associated contact, side switch arm 2O tov ground. Relay 32 is energized in this circuit and completes a circuit from grounded l battery, winding of slow releasezrelay 3.5,

armature and front contactiof relay 32 .to ground.

Assuming that the number of the wanted subscriber is 23 the calling subscriber will now operate his impulsesending device 34 to send the firstseries of.impulsesfcomprising a train of two impulses. y As a result relay 32 will be deenergized twotimes. Upon the first deenergization of relay 32 a circuit is completed from'grounded battery, winding of stepping magnet 36 of the tens register, conductor 37, side switch arm 38, winding of slow release relay 39, armaturel and front contact of relay 35, which, being slow to release, remains energized during the sending of the impulses, armature and back contact of relay 32 to ground. Magnet 36 is energized and as soon as relay 32 again'energizes the stepping magnet deenergizes to 40 and 41 into engagement with the first off-normal terminals in their respective banks.` Slow release relay 39 is energized in series with stepping magnet 36 and remains energized until the completion' of the sending of the first set of impulses. tens register makes a step' upon each vdeenergization of relay 32 and is therefore in its second off normalposition when the sending of the first. series of impulses is completed.' c

After the first series of impulses has been sent, stepping relay 32 will remain energized over arelatively long period of time, Y

thuscausing the deenergization vof relay 39. It is lto be noted that while relay 39 was energized side switch stepping magnet 42 was energized by a circuit extending from grounded battery, winding of magnet 42, armature and frontcontact of relay 39 to ground. rlhe side switch comprises arms 43, 38 and 44, and is a simple rotary switch controlled by magnet 42, which in each position therefore causes-the deenergization of magside switch controlled by it into position 2.

With the sender side switch in position 2,

a circuit. is completed from ground, power magnet of sequence switch 45, upper leftliand contact of sequence switch spring 46, side switch arm 43 and its second contactto ground, for moving this sequence switch out of position 1 and into position2.

The calling subscriber now operates his dial to send three impulses to record the units designation on the units register, which comprises brushes 47 and 48 with their associated contact banks and a controlling stepping magnet 49. The iirst interruption of the line circuit causes vrelay 32 to be deenergized and completes a circuit from grounded battery, winding of magnet Thecause the advance of tens register brushes causes the switch to be advanced upon de- 'energization The deenergization of relay39 49, `conductor 50, side switch arm 38 and l contact of relay 32 to ground. vRelay 39 is l energized and causes in turn the energication of side switch stepping magnet lllagnet 49 is energized and when relay again deenergizes causes the brushes 47 and 48 to engage their lt oft-nor contacts., The ahoye described operation continues until all the impulses have heen sont, at which tiine brushes and will he in engagement with 'their third oil"- norn'ial contacts. rlie continued energizetion of relay 32 causes the release of relay 39, which, upon deenerginatioi'i, cznses the release or stepn-ing nagnet 42, w ich advances the side smi l it h aiins contiolicd into engagement "ith their third contacts is soon as serpience switcn e reaches its second position the fundamental circuit is closed to start the selective operation ci" the switch shown in Fig. 2, This circuit completed :troni the grounded battery, winding of relay 51, lower lett-hand contact of sequence switch spring 52, conductor 53, winding or stepping inagnet 54, contact oli sequence switch spring 55, outer arinature and hack contact or' theo" conntii L; relay, conductor 56, lower left-hand contact ot sequence switch spring 57 to ground. Relay 51 is energized in this circuit and locks up to 'conductor 53 by way of its righthand armature and front contact and the upper left-hand contact oli sequence switch spring 52. rl`he energization or relay 51 also completes a circuit frein grounded 1cattery, winding oir' the power inagnet ot sequence switch 58, lower right-hand contact of scquence switch spring 59, left-hand arinature and front contact of relay 51 to ground, for moving this sequence switch ont of position 1 and into position 2.

lt is to be observed that stepping relay 54 was energized in series Yith line relay 51, thus completing a circuit roin groundec battery, winding` of the No. 1 counting relay, armature and hack contact oi the No. 1 counting relay, conductor 60, register brush 41 and its second contact, left-hand contact of sequence switch spring 61, arinatnre and front contact of relay 54 to ground. rl`he No. 1 counting relay is energized in this circuit and prepares in the well-known inanner a circuit 'for the No. 1 counting relay.

Vtith sequence switch 58 in position 2 and with relay 51 energized a circuit is completed from grounded battery, winding of up drive power magnet G2, contact of sequence switch springf, left-hand armature and 'iront contact oli relay 51 to ground. The energization of inagnet 62 causes the brush shalt which carries brushes 64, 65 and G6 to be nioved npwardlyin a group selecting inoveinentK is soon as coinn mutator brush 67 engages the first conducting segment of commutator 68, stepping relay 54 is shunted down, since ground "s new directly right-hand contact or sequence ^f 52, conductor 69, coininutator tor brush GY to ground. When i; g relay deencrgizes the shunt iiroin about the winding of the ucting segment of con'nnntator GQ, 54 again short circuitcd and allows f relay to he energized.

of 'the O counting y cuit tohe con'ipleted 'troni i, power niaffoet of sequence right-hh l contact oi h spring 45, conductor TO, and front contact oit the c arn'iatnre ner counting relay 4to ground for inming fh-pience switch out or position u position 3, thus opening the wer branch of the ;t`undaniental circuit. ifi/Then coininutator brash' 67 engages the next insnlat ne segment ot coinniutator 68, at which tiine hrashes 64, 65 and 66 will he in operative relation to the group or lines nun'ihcred 21 to 30, the locking circuit or 'opened and this relay deenci'- i' ,f 5l is sizes, openinO1 'the circuit o' up drive inag- D 'E3 n net and bringing the selector shalt to rlhe deenergization of relay 51 also inpletes a circuit from grounded battery, power magnet of sequence switch 58, lower icft-hand contact of sequence switch sprine 59, lett-hand arinatnre and hack contact or relay ground for moving this sequence switch out ol position 2 and into position lillhen sequence switch 45 reaches position 3, it is in'nnediately ino'ved into position 4 hy a circuit extending troni grounded hattery, power inagnet o1' sequence switch 45, upper righthand contact of sequence switch spring 46, side switch arrn 43 and its third contact, to ground, provided that the units Yregister has heen positioned. lf the units impulses have not yet been set, the side switch will he in position Q. Therefore, 'the sequence switch 45 will wait until the units register has been positioned as evi- .denced hy the advance of the side swit h into position 3.

is soon as sequence switch 45 reaches position 4, relay 51 is again energized oy ineans of a circuit extending 'from grounded battery, winding of relay 51, lower leithand contact of sequence switch spring 52, conductor 55; winding of stepping relay 54, contact of sequence switch spring 55, outer arma-ture and back contact of the O countinfr relay, conductor 56, lower left-hand contact of L,eq-tienes switch spring 57 to ground.

to relay 51 hy way o if The energization of relay 51 completes a. circuit from'grounded battery power magnet of sequence switch 58, lower right-hand contact of sequence switch spring 59, lefthand armature and front contact of relay 51 to ground, for moving sequence switch 58 out of position 3 and into Vposition 4. Inposition 4 of sequence switch 58, relay 51 is maintained energized by means of a locking circuit extending throughl its righthand armature and front contact. At its left-hand armature and front contact relay 51 supplies ground to up-drive power magnet 62 to cause the brush shaft to be moved upward.

Stepping relay 54 is energized upon the completion of the fundamental circuit, and completes ay circuit from grounded battery, winding of the No. 2 counting relay, armature and baclr contact of the No. 2counting relay, conductor 71, register brush 47, and its third olf-normal contact, contact of sequence switch spring 61, armature and front contact of relay 54 to ground. The No.2 counting relay is energized in this circuit in the well-known manner and prepares a circuit for the No. 2 counting relay, which is not energized at this time, dueto the shunt circuit to ground completed atV the armature of relay 54. 1

As the selector brush shaft is moved upward, commutator brush 72 is advanced into engagement with a conducting segment of commutator 73. As soon as this occurs, re lay 54 is shunted out and relay 51 is maintained energized by a path extending to ground by way of the lower righth-and con- Vtact of the sequence switch 52, conductor 74',

commutator 73 commutator brush 72 to ground. The deenergization of relay 54 allows the No. 2 counting relay to energize. As soon as commutator brush 72 engages an insulating segment of commutator 7 3, relay 54 is again energized and allows thel No. l counting relayY to be energized. As the shaft moves upward relay 54 is intermittently operated to cause the operation of the counting relays. When the 0 counting relay is energized, a circuit is completed from grounded battery, power magnet of sequence switch 45, lower right-hand contact of sequence switch spring 46, conductor 7 0, inner armature and front contact of theAG counting relay to ground, for moving this sequence switch out of position 4 and into position 6. The advance of the selector brush shaft continues until commutator brush 72 engages an insulating segment of commutator 73, at which time the brush set comprising brushes 64, and 66 will be accurately centered at the terminals of. the wanted line. Relay 51 thereupon deenergizes and opens the circuit of Lip-drive magnet 62 and at its left arma- "ture and back contact completes a circuit from grounded battery, power magnet of sequence switch 58 lower left hand contact of sequence switch 'spring 59, armature Vand back contact of relay 51 to ground for moving this sequence switch out of position 4 and into position 12. p

It is to be understood that in practice sequence switch 58 would be brought tol rest in various positions between 4 and 12, in or# der to accomplish a test to determine whether the called line is busy, and to supply ringing current to the line of the called subscriben if idle. Since these operations are well-known in theart and are not essential to the invention, they have been omitted from the present description, and it will be assumed that the calledv line was properly signaled,- and that the response of thecalled subscriber caused thek advance of sequence switch 58 into position 12. y,

As soon as sequence switch 45 leaves position 4, the energizing circuit of escape mag' net 9, which controls the line finder side switch is interrupted vat the upper left-hand contact of sequence switch 26, and this magnet deenergizes and advances thel line finder side switch into position 5.

ln position 5 of the line finder side switch and position 12 of the selector switch 58, the talking connection is complete, being `'eX- tended over an obviously traceable circuit through side switch arms 2() and 21 and their fifth contacts, and sequence switch springs 75 and 7 6to the left-hand windings of a repeating coil 77 which supplies battery to .the substation of the calling subscriber. Calling supervisory Arelay 78 is energized for a purpose which will appear later. Talking battery is supplied to the called subscriber through the righthand windings of repeating coil 77, by. way of sequence switch contacts 79 a-nd 80, and brushes 64 and 65- and their associated contacts. Current flow in the loop of the called subscribers line causes the energization of the supervisory relay 81 for a purpose to be set forth hereinafter.

It is to be observed that when sequence switch 58 reaches position 11 the called subscriber-s cut-off relay 82 is energized to remove the control of the subscribers line relay, `by means of a circuit'extending from vgrounded battery, winding of relay 82, terminal brush 66, contact of sequence switch spring 84 to ground.'

It will be recalledfhat after the selective operations. are completed, sender sequence switch 45 is advanced into position 6.Y The next stopping position of sequence switch 45 is determined by thecondition of relays 18 and 19. In 'the 'present case, since the l Vcalling line is a direct line, and therefore re-v lay 19 only is energized, sequence switch 45y is vmoved out of position 6 and into position 8- by means of a, circuit extending from grounded battery, power magnet of sequence switch 45, conductor 95, lett-hand contact or sequence switch spring 88, conductor 98, right-hand armature and iront contact of relay 19, lett-hand armature and back contact of relay 18 to ground.

When conversation is completed the calling and called subscribers will replace their receivers and thus bring about the deenergization ot relays 78 and 81. The deenergi- Zation oic relay 78 completes a circuit from grounded armature and back contact of relay 78, upper contact of sequence switch spring 85, conductor 98, winding ot power magnet of sequence switch. 58 to grounded battery thus causing the advance of sequence switch 58 out of position 12 and into position 16. 1n passing 'through positions 14 and 15 charging current would have been supplied in case the calling line had been either a coin box line or a message register line. Since the line is a. direct line no cnargine"y current of any kind is supplied.

`When sequence switch 58 reaches position 16 a circuit is completed from grounded batte-ry, pow r magnet of sequence switch 45, lower Contact of sequence switch spring 91, conductor 99, upper lett-hand contact of sequence switch 57 to ground, for moving thisl sequence switch out of position 8 and into position 16. As soon as sequence switch 45 reaches position 11 a circuit is completed from grounded battery, power magnet of sequence switch 58, conductors 98 and 100, upper contact of sequence switch spring 91, conductor 99, upper contact or sequence switch spring 57 to ground, for moving this sequence switch out of positionl 10 and into position 17. Sequence switch 58 remains in lposition 17 until the/,line finder has been restored to its normal position.

Referring now to the sendercircuits, release oit the registers take place as soon as sequence switch 45 reaches position 16. The units register is the first to release and is advanced into its normal position by means ot a circuitY extending from Grounded battery, winding of stepping magnet 49, armature and bach Contact o't magnet 49, register arm 48, and auroit-normal terminahcontact ot sequence switch spring 101 to ground. Magnet 49 interrupts its own circuit until the register brushes 47 and 48 reach their normal positions. kAs soon as brush 48 reaches its normal position, a self-interrupting circuit is completed for the tens register magnet. This circuit extends from grounded battery, winding oit magnet 86, armature and back contact of magnet 86, register arm 40 and oit-normal contact, the units register arm'48 and the normal terminal, contact of sequence switch spring 101 to ground. Stepping magnet 36 advances the tens registerV into its normal position, in which position the above traced circuit is opened, As soon restan-iY as the registers have been returned to their normal positions, the sender side vswitch is returned to its normal position since a seltinterrupting circuit is completed for side switch stepping magnet 42. This circuit ezitends from grounded battery, winding ot magnet 42, armature and bach contact o` magnet 42, side switch arm 44 and its third contact, tens register brush 40 and its normal contact, units register brush 48 and its normal contact, contact of sequence switch spring 101 to ground. Magnet 42 advances the side switch one step into its normal position, whereupon a circuit is completed from grounded battery, power magnet of sequence switch 45, upper contact of sequence switch spring 102, side switch arm 44 and its non mal contact, register brushes 40 and 48 and their respective normal contacts, contact oi sequence switch spring 101 to ground, Jitor moving this sequence switch out oit position 16 andl into position 1. All parts ot the sender apparatus have now been restored to their normal condition.

ln position 17 of sequence switch 58, the line finder switch shown in Figure 1, is restored to its normal position due to the completion ot a self-interrupting circuit for line inder stepping magnet 12. This circuit eX- tends from vgrounded battery, winding of magnet 12, armature and back contact of magnet 12, conductor 104, contact of scquence switch spring 87, conductor 105, o"- normal segment 108, brush 17 to ground. Magnet 12 advances the line finder switch until brush 17 leaves off-normal segment 108, which time the line iinder will have been advanced into its normal position. The re turn of the line finder switch causes the restoration of the line finder side switch in any welldrnown desired manner.`

lilhen the line finder switch reaches its normal position, a circuit is completed from grounded battery, power magnet of sequence switch 58, conductor 98, lower lett contact of sequence switch spring 85, conductor 100, normal iinder contact 104, brush 17 to ground, for moving sequence switch 58 out of position 17 and into position 18.

1n position 18 of sequence switch 58 the selector switch is restored. This is accomplished by down drive magnet 94, due to the completion of a circuit extending from grounded battery, winding of magnet 94, upper left-hand contact of sequence switch spring 57 to ground. As soon as commutator brush G7 engages normal commutator segment 1.07, a circuit is completed from grounded battery, power magnet of sequence switch 58, upper right-hand contact ott sequence switch spring 59, segment 107, brush 67 to ground, for moving this sequence switch out of position 18 and into position 1. As soon as sequence switch 58 leaves position 18, the circuit of down drive magnet inseguirek 94 is opened and the selector brush shaft is brought to rest. All parts of the apparatus have now been restored to their normal positions and are ready for reuse. y

The operation of the system in case a call is originated by a subscriber equipped with but a coin collect device will now be de-v scribed. A subscribers substation apparatus orn this character is indicated at 107. In this case the operation of the system is identical with that previously described up to the point immediately following the seizure of the calling lineby tne line iinder switch. As before, relays18 and 19 are given an opportunity to energize in position 3 of the line finder side switch, while awaiting the energization of slow pull-up relay 28. In the present case, relay 19 is energized by a circuit extending from grounded battery, right-hand winding of relay 19,

side switch arm 20 and its third contact, brush 14e, conductor 115 thence through the loop of the calling substation, outer armature and bach contact of relay 108 to ground. Relay 18 is also energizedlo'y a circuit extending from grounded battery, left-hand winding of relay 18, side switch arm 21 and its third contact, brush 15 and its associated contact, conductor 116, outer armature and back contact of relay 108 to ground. It is to be observed that relay 419 is shunted by the winding of relay 109, but since relay 109 is a high .resistive relay, relay 19 is allowed to be operated. Relays 18 and 19 upon energization lock up to conductor 25 Vas previously described.

From this point the operation of the system is the same as previously describeduntil after the selector switch has been .positioned and the sender sequence switch `has Y been advanced ont of position 4 and into position 6. Sequence switch 115 is then advanced out of position` 6 through position 8 .and into position 10 by means of a circuitextending from grounded battery, power magnet by sequence switch 15, conductor 95,V

upper right-hand contact of sequence switch spring 88, conductor 97, armature and front contact ofrelay. 18 to ground; lnposition 10 of sequenceswitch 45 proper conditions are set up so that in case' of a successful call coin collect current will be supplied to coin collect magnet 119.

Assuming, that a call has been successful and that the called subscriber has-answered, his responsewill cause the energization of relay 81. A circuit is then completed from grounded battery,.winding of `relay 92, contact of sequence switch spring 90, varmature and front contact of relay 81 to ground. Relay 92 upon energization locks up through its right-hand armature and front contact.

`.When connection is no longer desired release takes place as previously :dcscribed. When sequence switch 58 reaches position v 14, and Vwhile passing through this position and through position 15, coin collecteurrent is supplied by way of the left-hand armature and front contact of relay 92 to the lower contact of sequence switch spring Vthe calling subscriber replacedhis receiver,

release woiild have taken place as previously described. j ln this case, however, ground return current would. have been supplied to ,the tip conductor of theline by wayof the left-hand armature and back contact of relay 92., rllhe restoration of this system after reaching position 16tales place'ina manner identical with that previously described. The operation of the system in case a call is originated by a subscriber whose line is equipped with a message register will now be described. A substation of this characf ter is indicated at 4110, and, isV shown withr an associated line relay 112, cut-on" relay 111, and message register .device '113. 1n this case, the right-hand winding fof line relay 112 is of low resistance, corresponding to that ofV the. winding of line'relay 2 of a direct line, while the left-hand winding of relay 112 is of a relatively high resistance. 1n 'this case the operation of this system takes place ias Y previously described until that stage is 'reached at which circuits are completed for relays 18 and 19. 1n thev present case neither' of theserelays will be energized. Relay 18 will vnot energizesince its left-hand winding extends to ground through the high resistance left-hand winding of relay 112. Relay'l) does not become energized since its right-hand winding is shnnted by the low resistance right-hand winding-of relay 112. The operation of this system continues as above set forth. ln the present case when sequence switch 15 reaches position 6, it remains in this position since neither' of the paths for advancing'it controlled by relays 18 and 19, have beenA completed. Afterthe connection has beenl completed it may. be released 'bythe calling subscriber. as previously described. quence switch 58 passes through positions 14 and 15 an increased potential is supplied to the sleeve conductor tooperate the message register from source of potential 93, contact of sequence switch spring 86,` conductor 120, brush 16 and its' associated contact,

1n this case when selel to round. From this point the operation o the system is identical with that previously described.

From the toregoing it is obvious that the position assumed by the sender sequence switch is the controlling factor which determines whether or not a charging current is to be supplied to the calling line, and in case charging current is required it also determines the character of current to be supplied. lt is also obvious that the relays 18 and 19 control the selection of the sequence switch charging position, and that these relays are in turn dependent upon electrical characteristics oit the calling line tests.

ln order to bring out more clearly tlie operativeness of the systems, the following characteristics are suggested. in connection with relays 18 and 19. Relay 19 will operate on direc-t ground but will not operate on ground through e high resistance, sucli as the lett-hand winding of relay 119,. Neither will relay 19 operate when shuntcd by the low resistance such a the right-hand winding of relay 112. Relay 18 will operate on direct ground but will not operate when shunted by a low resistance such as the winding ciz line relay 2. Neither will it operate in series with high resistance suoli as the left-hand winding of relay 112.

W hat is claimed is:

1. ln a telephone exchange system, calling subscribers lines equip Jed Jfor various classes oi" service, called subscribers lines,v

an automatic switch for interconnecting calling and called subscribers. lines, a registering device, means to operate said regis:n vteringdevice to record the class of service to which Vthe calling line is entitled, charging means, and automatic means to govern the operation of said charging means-in accordance with the setting ot said registering device.

2. ln a telephone exchange system, calling and called subscribers lines, an automatic switch for interconnecting said lines. certain ones oit said calling lines being equipped with coin collect devices, others of said calling lines being` equipped with message registers, and others of said calling lines being flat rate lines. means for ext-ending a calling line to said automatic switch, charging means, and discriminating means automatically ccntrolled in accordance with the class oi service to which the calling line is entitled, to govern the operation of said charging means.

3. ln a telephone exchange system, calling subscribers lines equipped for various classes of service, called subscribers lines, an automatic switch for interconnecting said calling and called subscribers lines, means for extending a calling line to said automatic switch, a registering device, means to Laramie operate said registering device to record the class ci service to which the calling line is entitled, charging means, and automatic means to govern the operation ci said charging means in accordance with the setting ot said registering means.

4l. ln a telephone exchange system, calling subscribers lines equipped for various classes of service, called subscribers lines, an automatic switch tor interconnecting calling and called subscribers lines, means governed by a calling subscriber to control the operation oi said automatic switch, a registering device, means to operate said registering device to record the class ot service to which the calling line is entitled, charging means, and automatic means to govern the operation of said charging means in accordance with the setting of said registering means.

ln a telephone exchange system, calling and called subscribers lines, an automatic switch 'ter interconnecting said lines, certain ones or" said calling lines being equipped with coin collect devices, others of said calling lines being equipped with niessage registers, and others of said calling lines being dat rate lines, automatic means for extending a calling line to said automatic switch, charging means, and discriminating means automatically controlled in accorda-nce wit the class of service to which the calling line is entitled, to gvern the op eration ot said charging means.

6. ln a telephone exchange system, calling subscribers lines, equipped for various classes or service, called subscribers lines an automatic switch for interconnecting calling and called subscribers lines, an automatic switch for extending connection from a calling line to said automatic switch, a registering device, means to operate said registerin device to record the class of service to which the calling line is entitled, charging means, and automatic means to govern the operation ot said charging means in accordan with the setting ot said registering device.

'7. ln a telephone exchange system, callin and called subscribers lines, an automatic switch for interconnecting said lines, certain ones oic said lines being equipped with coin collect devices, other of said calling lines being equipped with message registers, and others oil said calling lines being direct lines, y calling line to said automatic switch, a contact banlr igor said distributing switch in which said callin.,` lines terminate, means to suppli characteristic potentials to said terminals in accordance with the class ot serv.- ice to which a calling line is entitled, a group of relays, variably operative charging means, and means to energize said relays in various combinations to control the operation of said charging means.

a distributing switch lor extending a ist:

8. In a telephone exchange system, calling and called subscribers lines, means for interconnecting said lines, said calling lines being equipped for Various classes of serv- 5 ice, means toy supply said calling lines With characteristic electrical potentials in accord- Y ance with the class of service to which said Alines are entitled, and a discriminating. de-

to govern the charging cf calls to'said call- 10 Y ing lines. v

In Witness whereof I hereunto subscribe my name this 17th day of December A. D. 1920. i e

i ALBEN E. 'LUNDELL 

